WO1996002739A1

WO1996002739A1 - Device for the simultaneous actuation of at least two gas shuttle valves

Info

Publication number: WO1996002739A1
Application number: PCT/EP1995/001496
Authority: WO
Inventors: Johann Kecker
Original assignee: Ina Wälzlager Schaeffler Kg
Priority date: 1994-07-19
Filing date: 1995-04-20
Publication date: 1996-02-01
Also published as: DE9411680U1

Abstract

A device for the simultaneous actuation of at least two gas shuttle valves (2) takes the form of a bridge (3). To separate the bridge (3) from a lifting movement of a cam (4), according to the invention a lockable and unlockable cam follower component (7) can be applied in the bridge (3).

Description

description

Device for the simultaneous actuation of at least two

Gas exchange valves

The invention relates to a device for the simultaneous actuation of at least two gas exchange valves of an internal combustion engine with a bridge, which is arranged in a driving manner between a control cam and the gas exchange valves and is axially movably supported by end guide columns with respect to a cylinder head of the internal combustion engine, the bridge on its the end facing the control cam, in the area of its transverse center plane, has a cam starting element communicating with the control cam and cooperates with the gas exchange valves in the stroke direction on its end remote from the cam.

Such a cam follower is previously known from DE-A 40 23 886. This also consists of a bridge-shaped housing, which is acted on by a cam and at the same time acts on two gas exchange valves. A disadvantage of the known cam follower is that it is permanent, i.e. H. is effective even at low speed / load. In this operating state of the internal combustion engine, for example, it would be desirable to shut down entire cylinders or rows of cylinders (V engines) in order to achieve fuel savings or emission minimization of exhaust gases.

Devices are known from the prior art for the simultaneous actuation of two gas exchange valves with an optional change in the opening stroke, but this must be based on different cam con doors can be used. This arrangement disadvantageously requires three cams and causes a high loss of friction, since the cam lift on the respective valve is removed via a sliding tap (see US Pat. No. 4,955,639).

The invention is therefore based on the object of providing a device for the simultaneous actuation of at least two gas exchange valves of an internal combustion engine, in which the disadvantages mentioned at the outset are eliminated and in which, in particular via a simply constructed mechanism, a safe valve shutdown of several simultaneously acting valves Gas exchange valves is realized.

According to the invention this object is achieved by the characterizing part of claim 1 in that the cam starting element is produced as a roller guided in a longitudinally movable piston or a slide formed thereon for drivingly decoupling the bridge from the lifting movement of the control cam, the piston being in a cam-side Bore of the bridge runs and is supported on its underside by the force of a pressure medium in the cam direction and at least one displaceable coupling means is arranged in the bridge, which at least in the case of coupling intersects an annular surface formed between the piston and its bore and at the same time in one complementary recess of the piston runs. This measure creates a simple valve shutdown, in particular for multi-valve technology, without complex changes to existing camshafts or cylinder heads. A low-wear switching operation is guaranteed at the same time by the cam-starting element that constantly starts at the control cam. It is also conceivable and envisaged to achieve only partial strokes of the relevant gas exchange valves by means of coupling means positioned in a height-distributed manner in the device. When choosing an axially movable slide tap in the bridge, it can be provided that this slide tap is suitably Layer. It is particularly advantageous if the cam start element in the base circle of the control cam projects only slightly beyond the bridge in the cam direction. Thus, the overall height of the entire device is influenced favorably and, if necessary, existing connection dimensions can be used. Instead of the piston described here, other elements are also provided as cam counter-rotors which are suitable for carrying out an oscillating movement in the bridge, for example also bar-shaped and similarly suitable ones.

Further embodiments according to the invention are the subject of subclaims 2 to 15.

A conical spring is provided as pressure medium for the cam starting element. By choosing this conical spring, the space required for the pressure medium in the bridge is minimized. Other pressure means are also conceivable and provided, such as magnetic, electromagnetic and other suitable ones, as well as other mechanically acting ones.

From claim 4 shows a preferred arrangement of the coupling means in the bridge. It can also be provided to arrange at least two coupling means positioned in the bridge, which include the cam start element. The coupling means can also be positioned parallel to an imaginary connecting line between the guide columns. The scope of this invention also includes a solution in which the coupling means runs approximately radially to the cam start element.

In concretization of the invention it emerges from a further subclaim that it is provided that the coupling means is reset via a

To cause compression spring. Nevertheless, a reversal of the kinematic principle just described is the subject of the invention, in which a Movement of the coupling means into its uncoupling position via the force of at least one compression spring and displacement of the coupling means into the coupling position via the force of the pressure medium is produced.

A supply of hydraulic fluid to the hydraulic piston designed as a coupling means is produced in one embodiment of the invention via one of the guide columns. Provided that hydraulic play compensation elements are used, the supply of the play compensation elements is realized via the respective other guide column. It may also be conceivable to produce a common supply of the coupling means and the play compensation elements via only one guide column. It is also conceivable to design the bridge in the form of a fork in the area of one of the guide columns and to encompass the relevant guide column by the fork. As a result, changes in length can be compensated for in a simple manner by thermal expansion.

In an embodiment of the invention, it is provided in claim 10 to produce an anti-rotation device for the piston by means of a pin which projects beyond the annular surface between the piston and its bore. It is also envisaged to give the piston or the cam start element such a non-rotationally symmetrical geometry, by means of which twisting in the relevant receptacle is prevented in any case.

A particularly low-friction cam tap in the piston is produced in that the roller runs on a pin above a roller bearing. Instead of the roller bearing, a slide bearing is also considered. The piston can also be dome-shaped in the region of the roller and the roller can be supported on a plurality of rolling elements in the direction remote from the cam.

From claim 12 it appears that it is provided that the bridge and / or the cam start element made of a lightweight and / or polymeric material to manufacture. This measure creates a further contribution with regard to mass reduction and lowering of the oscillating masses in the valve train. This leads to a reduction in the friction, the required valve spring forces can be reduced or the maximum speed of the internal combustion engine to be driven can be increased.

If the coupling means is conical at least on its side facing the cam start element, a particularly secure locking of the piston in question is created in the event of a coupling, since a certain tolerance compensation is guaranteed.

Finally, claims 13 to 15 show that it is also intended to apply mechanical play compensation in the bridge. On the one hand, it is conceivable to place a simple screw in a hole in the bridge against the end of the valve stem. However, other setting elements, such as bolt-like ones, are also conceivable and provided, which can have exchangeable setting plates or the like at their end facing the gas exchange valve. A nut is used here to simply secure the screw in position.

The above-mentioned measure makes it possible to dispense with the oil supply to the hydraulic elements that are otherwise used. By using defined thread pitches there is no need for time-consuming measuring of the valve clearance that occurs. To make the setting, it is only necessary to count the number of revolutions of the screw.

The invention is not limited only to the features of its claims. Possible combinations of individual claim characteristics and possible combinations of individual claim Features with what is disclosed in the information on advantages and the design example.

The invention is expediently shown in the drawing. Show it:

Figure 1 shows a longitudinal section through an inventive device;

Figure 2 shows a cross section according to Figure 1;

3 shows a partial view of Figure 1 with uncoupled Nockenanlauf¬ and

Figure 4 is a partial view of the bridge with mechanical play compensation elements.

1 shows a device 1 for the simultaneous actuation of at least two gas exchange valves 2. This device 1 consists of a bridge 3, which is operatively positioned between a control cam 4 of a camshaft, not shown, and the gas exchange valves 2. The bridge 3 is guided at the end via guide columns 5 opposite a cylinder head of the internal combustion engine (not shown). It is also conceivable here to firmly connect the guide columns 5 to the bridge 3 and to produce the entire device so that it can move axially relative to the cylinder head. In the area of its transverse center plane, on its end face 6 facing the control cam 4, the bridge 3 has a longitudinally movable piston as a cam starting element 7. A roller 8 is arranged in the cam start element 7. This roller 8 runs on a pin 9 above a roller bearing 10. The roller 8 is thus produced as a low-friction counter-rotor for the control cam 4. The cam start element 7 is supported by a pressure medium 11 against a base 12 of a bore 20 for the cam start element 7. Ande- on the one hand, the pressure medium 11 acts on an underside 13 of the cam start element 7. In this variant, the pressure medium 11 is designed as a conical spring. It is also conceivable to apply a plurality of such springs, which can also be cylindrical, to support the cam starting element 7.

A hydraulic lash adjuster 14 is assigned to each gas exchange valve 2 in the bridge 3. A supply of hydraulic fluid to the play compensation elements 14 is established via one of the guide columns 5. For this purpose, this guide column 5 has an axial bore 15 out of the cylinder head of the internal combustion engine, which communicates with an oil supply gallery in the cylinder head. This axial bore 15 is connected to a radial bore 16 in the guide sleeve 5. A transverse bore 17 runs in the bridge 3 parallel to its end face 6 (see also FIGS. 2, 3). This cross-bore 17, which synergizes at least over partial sections of a stroke of the bridge 3 with the radial bore 16, provides a sufficient supply of the relevant play-compensation elements 14 with hydraulic medium. Via a further axial bore 18 in the further guide column 5, a coupling means 18a displaceable in the bridge 3 parallel to the camshaft direction is realized.

This coupling means 18a, here in the form of a piston, extends tangentially to an annular surface 19 between the piston as the cam starting element 7 and its bore 20 surrounding it. In the case of a coupling of the bridge 3 to the lifting movement of the control cam 4, the cam starting element 7 has on its underside 13 a complementary recess 21 for the coupling means 18a in the area of the coupling means 18a. Seen in the longitudinal direction, the piston also has an annular recess 22 as the coupling means 18a (see FIG. 2). On a first end face 23, the coupling means 18a is acted upon by hydraulic means from a transverse bore 24. This cross bore 24 is again during certain lifting sections of the bridge 3 with a radial bore 25 through the guide column 5, which is not used to supply the play compensation elements 14. This radial bore 25 opens into the axial bore 18 of the guide column 5 in question. On a further end face 26 of the coupling means 18a, a compression spring 27 is applied, which on the other hand is supported on the base 28 of the bore 29 surrounding the coupling means 18a.

If a decoupling of the bridge 3 from the lifting movement of the control cam 4 is desired, as a result of which the relevant gas exchange valves 2 remain closed, the coupling means 18a is axially displaced in its bore 29 by hydraulic means in the direction of the base 28. The actual piston surface of the coupling means 18a thus comes out of engagement with the recess 21 on the underside 13 of the cam starting element 7. Since the recess 22 of the coupling means 18a is now cut directly by the cam starting element 7, this can move axially freely in its bore 20. The cam start element 7 thus follows the lifting movement of the control cam 4 against the force of the pressure medium 11 (see FIG. 1). Due to the idle stroke of the cam start element 7 with respect to the bridge 3, the gas exchange valves 2 in question remain closed. A coupling of the cam starting element 7 to the lifting movement of the control cam 4 is preferably implemented in a base circle phase of the control cam 4. For this purpose, the pressure of hydraulic medium applied to the end face 23 of the coupling means 18a is minimized in such a way that the coupling means 18a is pushed into its coupling position by the force of the compression spring 27. In this position, the coupling means 18a engages with partial sections of its piston surface in the complementary recess 21 of the cam starting element 7 facing it. This coupling restores the frictional engagement between the cam starting element 7, bridge 3 and gas exchange valves 2. The gas exchange valves 2 open in the sense of the stroke contour of the control cam 4. A recess 30 is provided in the bore 20 of the bridge 3 for the coupling means 7. A rolling element 31 runs in this recess 30. This rolling element 31 projects radially inward beyond the annular surface 19. At the same time, it runs in a complementary recess 32 of the cam starting element 7, which is designed here as a longitudinal groove. This measure makes the cam starting element 7 easy to twist realized opposite the bridge 3.

FIG. 3 shows the cam start element 7 in its uncoupled position. With its outer jacket 33, the cam start element 7 cuts the cutout 22 of the coupling means 18a.

Finally, FIG. 4 shows in a partial view of bridge 3 that it is also intended to use mechanical play compensation 35 instead of the hydraulic play compensation elements 14 used. This mechanical clearance compensation 35 is advantageously designed as a screw and runs in a bore 36 of the bridge 3 aligned with the gas exchange valves 2. The screw 37 is seated with its end 37 directly on one end 38 of the gas exchange valve 2. In its head region 39, which faces away from the end 37, the screw is provided with a nut 40 as a securing element. By turning the mechanical lash adjuster 35 designed here as a screw, an adjustment of the valve lash is made possible.

LIST OF REFERENCE NUMBERS

1 device 22 recess

2 gas exchange valve 23 end face

3 bridge 24 cross hole

4 control cams 25 radial bore

5 guide pillars 26 front

6 face 27 compression spring

7 cam start element 28 reason

8 roller 29 hole

9 bolts 30 recess

10 rolling bearings 31 rolling elements

1 1 pressure medium 32 recess

12 reason 33 outer jacket

13 underside 34 end face

14 backlash compensation element 35 mechanical backlash compensation

15 axial bore 36 bore

16 radial bore 37 end

17 cross bore 38 end

18 axial bore 39 head area

18a coupling agent 40 nut

19 ring surface

20 hole

21 recess

Claims

Expectations

1. Device (1) for the simultaneous actuation of at least two gas exchange valves (2) of an internal combustion engine with a bridge (3) which is arranged between a control cam (4) and the gas exchange valves (2) and opposite via end guide columns (5) A cylinder head of the internal combustion engine is mounted so as to be axially movable, the bridge (3) on its end face (6) facing the control cam (4), in the region of its transverse center plane, having and engaging with a cam start element (7) communicating with the control cam (4) its end (34) remote from the cam cooperates with the gas exchange valves (2) in the stroke direction, characterized in that the cam start element (7) as a roller (8) guided in a longitudinally movable piston or a slide piece formed thereon for drivingly decoupling the bridge ( 3) is produced by the lifting movement of the control cam (4), the piston running in a cam-side bore (20) in the bridge (3) and on its underside (13) is supported in the cam direction by the force of a pressure medium (1 1) and at least one displaceable coupling means (18a) is arranged in the bridge (3) which, at least in the case of coupling, has a coupling means between the piston and its bore (20) formed ring surface (19) cuts and at the same time runs in a complementary recess (21) of the piston.

2. Device according to claim 1, characterized in that the pressure means (11) is designed as at least one compression spring which is supported at one end on a base (12) of the bore (20) of the piston and the other end acts on the underside (13) of the latter .

3. Device according to claim 2, characterized in that the compression spring is designed as a conical spring.

4. Device according to claim 1, characterized in that the coupling means (18a) tangential to the annular surface (19) between the cam start element (7) and the bore (20) and is designed as a hydraulic piston with a recess (22), the hydraulic piston at least a first end face (23) can be acted upon by hydraulic medium and, in the event of a desired decoupling of the bridge (3) from the control cam (4), can be displaced in its bore (29) via the hydraulic medium in such a way that its recess (22) in the base circle of the control cam (4th ) the complementary recess (21) of the cam start element (7) opposite.

5. Device according to claim 4, characterized in that a further end face (26) of the coupling means (18 a) is acted upon by a compression spring (27) which is supported on the base (28) of the bore (29) against hydraulic medium pressure.

6. Device according to claim 4, characterized in that a Beauf¬ the hydraulic coupling designed as coupling means (18a) with hydraulic fluid via a guide column (5) from the cylinder head of the internal combustion engine, which has an axial bore (18) for the hydraulic medium which is orthogonally cut by a radial bore (25) in the region of the bridge (3), the radial bore (25) having at least one partial stroke of the bridge (3) with a transverse bore (24) through the bridge (3) to the bore ( 29) of the coupling means (18a) corresponds in the area of its first end face (23).

7. Device according to claim 1, characterized in that the bridge (3) is provided with hydraulic lash adjusters (14) which are applied to its end remote from the cam (34), with each gas exchange valve (2) facing a lash adjuster (14) .

8. Device according to claim 7, characterized in that a supply of the play compensation elements (14) with hydraulic medium via a guide column (5) is made out of the cylinder head of the internal combustion engine, which has an axial bore (15) for the hydraulic medium, which of a radial - Bore (16) in the area of the bridge (3) is cut orthogonally, the radial bore (16) communicating at least during a partial stroke of the bridge (3) with a transverse bore (17) through the bridge (3) to the play compensation elements (14) .

9. Device according to claims 6 and 8, characterized in that a supply of the coupling means (18) and a supply of the play compensation elements (14) is made via a first of the guide columns (5) and via a further one of the guide columns (5).

10. The device according to claim 1, characterized in that in the bore (29) of the bridge (3) for the coupling means (18 a) or in an outer circumferential surface (33) of the longitudinally movable cam start element (7) a rolling element / pin (31) as an anti-rotation device is fastened, which at the same time intersects the annular surface (19) located between the two elements (3, 7) and runs in a complementary recess (32) of the respective other element (7, 3).

1 1. Device according to claim 1, characterized in that the roller (8) on a bolt (9) over a roller bearing (10).

12. The device according to claim 1, characterized in that the bridge (3) and / or the cam start element (7) are made of a lightweight and / or polyme¬ ren material.

13. The device according to claim 1, characterized in that the bridge (3) is provided with a mechanical play compensation (35), wherein each gas exchange valve (2) is assigned a play compensation (35) and wherein each play compensation (35) runs in a bore (36) aligned with the gas exchange valves (2) and faces the gas exchange valves (2) directly.

14. The device according to claim 13, characterized in that the Spielaus¬ equalization (35) is made of one screw each arranged in the bore (36).

15. Device according to claim 14, characterized in that the screw in its head region (39), which projects beyond the end face (6) of the bridge (3), is provided with a nut (40) as a securing element.